1. Field of the Invention
This invention relates to a signal recording/reproducing method and apparatus for recording/reproducing signals on or from a signal record (recording, recordable or recorded) medium, a signal record medium having signals recorded thereon, and a signal transmitting/receiving method and apparatus for transmitting/receiving signal over a signal transmission medium.
2. Description of the Related Art
As a signal record medium for recording information signals, such as speech or various sorts of data, such signal record medium for optically recording the information signals, such as a compact disc for music or a CD-ROM employing the CD disc standard for data, is in widespread use. Recently, the standardization for a so-called digital video disc (DVD), as the next generation signal record medium, is also proceeding.
Meanwhile, the entire audio or video signals, for example, recorded on the signal record medium, such as CD, CD-ROM or DAD, may be read out by a reproducing apparatus and duplicated on another signal record medium capable of signal recording and reproduction, such as a hard disc, and the data thus copied on the hard disc may then be supplied to an encoder system for the CD, CD-ROM or DAD for formulating a new CD, CD-ROM or DAD, in order to prepare a CD, CD-ROM or a DAD having recorded thereon the same signals as those recorded on the original signal record medium.
If new signal recording media are produced in this manner one after another, it becomes impossible to discriminate whether the signals recorded on the signal record medium are original signals or copied signals. Of course, this problem is encountered not only in the disc-shaped record medium, such as the CD or CD-ROM, but also in a tape-shaped record medium or other signal recording media. It is therefore desirable that signals recorded on a given signal record medium can be identified to be original signals or copied signals. Although it has been practiced up to now to record in a pre-set area of the signal record medium the information specifying that original signals or copied signals have been recorded on the signal record medium, there lacks up to now a technique for identifying whether the signal is the original signal or the copied signal based on the signal itself.